PURPOSE: To simplify the constitution and to decrease the adjusting position by frequency-dividing an output of a PLL circuit making local oscillation for channel reception at a terminal device and using this output as an incoming data signal transmitting carrier frequency.

CONSTITUTION: A terminal device of a CATV system in which a center 1 and a lot of terminal device 10 are connected with a cable and bidirectional communication is made between the center 1 and the terminal device 10, is provided with a PLL circuit oscillating a frequency corresponding to a channel to be selected and a frequency division circuit 63 frequency-dividing an output frequency of the PLL circuit and outputting the result as a carrier wave frequency for an incoming data signal. A program and an outgoing data signal are transmitted from the center to each terminal device on a plurality of channels and the terminal device 10 transmits the incoming data signal to the center in the frequency of exclusive use corresponding to the selected channel.